Compute all given parts of following problem:

Problem: A vertical cliff is located at the edge of a lake, with the top of the cliff a vertical distance of 6.00 m above the water. A dog runs horizontally off the cliff with a speed of v0 as it leaves the edge of the cliff. The dog lands in the water a horizontal distance of 4.00 m from the edge of the cliff.

Part A: How long is the dog in the air?

Part B: What was the initial speed v0 of the dog?

I need help to determine the initial speed v0 of the dog.